Froth flotation of cement raw materials



Patented Dec. 7, 1943 MATERIAL David Walker Jayne, Jr., Old Greenwich, Stephen Edward Erickson,

Springdale, and Harold Milton Day, Cos .Cob, Comb, assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application September 28, 1940, Serial No. 358,830

11 Claims. (01. 209-166) ordinary fatty acids'are employed as collectors.

This invention relates to the froth flotation treatment of .cement raw materials and more particularly to the concentration of calcite from the usual gangue minerals found in argillaceous limestones,marls, and chalks to produce concentrates useful in the manufacture of Portland cement.

It has been known in the past that calcite could be concentrated by froth flotation operations in which the flotation was carried out in the presence of fatty acid oxide mineral collecting re-- agents, such as oleic acid and fish oil fatty acids. While these fatty acids have been used extensively, they are not entirely satisfactory in that it is very difficult to obtain satisfactory dispersion in the ore pulps and they cannot be effectively used in cold water. Also they are unsatisfactory for the concentration ofvery fine particles of calcite and particularly at normal pulp temperature which is believed to be due, at least in part, to incomplete dispersion and over-oiling which causes flocculation of the gangue materials resulting in concentrates of low grade. Emulsions of the above fatty acids are also not entirely satisfactory since they have a tendency to produce excessive frothing which results in the production of low grade concentrates. Similarly the sodium soaps of oleic acid and fish oil fatty acids result in the production of excessive froths of low grade which are inefficient as calcite collectors.

In accordance with the present invention we have found that the sodium salts or soaps of fatty acids containing less than 18 carbon atoms and preferably 8 to 16 carbon atoms are eflicient calcite promoters in spite of the general belief here-' tofore that sodium soaps could not be successfully used. The general experience-in the past has been that oxide minerals such as phosphate rock could not be effectively promoted using the sodium soaps of oleic acid or those of fish oil "fatty acids whereas they could be when the acids and alkali were added to the ore pulp separately. We have found, however, that ,the sodium soaps of individual'fatty acids containing from 8 to 16 carbon atoms, examples of which are sodium laurate, sodium myristate, and sodium palmate,

and the sodium soaps of mixtures of fatty acids inv which themixtures are made up of at least one third fatty acids containing not more than 16' carbon atoms, examples of which are the sodium soaps of the fatty acids of coconut oil, palm It is also an advantage of the present invention that our reagents are cheap; particularly the sodium soaps of' coconutoil, palm kernel oil, and

palm oil, which are produced simply by saponifying the respective oils with sodium hydroxide; and it is not necessary to remove the glycerine split off in the saponification reaction since the glycerine' does not appear to materially affect the promoter action.

Among the purposes of the invention are to provide a low cost but highly selective calcite 001- lecting reagent; to extend the practical use of flotation for the economical recovery of calcite from minerals of low commercial value, and to permit the-recovery of useful concentrates from slimy pulps which do not react successfully to flint and/orchalcedony; silicates of alumina, usukernel oil, and palm oil, are selective calcite promoters and are more effective than the common fatty acids such as'fish oil fatty 'acids and oleic acid now widely used.

The'reagents of the present invention are very easily dispersed in aqueous ore pulps even at low temperatures which is of decided value because it eliminates the necessity for the use of warm froth flotation with the fatty acid collectors. Some of the advantages of our reagents are that they can be diluted in water to any convenient degree to make possible light and uniform stage oiling; they are stable at all working temperatures and are quickly dispersed even in ice water; and

they are highly selective. These advantages extend the practical use of flotation to the recovery of the valuable content of cement raw materials such as the extremely fine grained material described as blue limestone of the Lehigh Valley district of Pennsylvania which are not readily amenable to flotation to produce concentrates of commercial grades, with the usual collectors, such as oleic acid, fish oil fatty acids, resin acids, soaps or emulsions, or mixtures thereof.

The principal minerals present in-cement raw materials are calcite; silica in the form of quartz,

ally oneor more forms of mica, but frequently as talc, feldspar, etc.; iron oxides, limonite and/or pyrite, and magnesia as dolomite, brucite, and/or combined with silicates of alumina, as for example phlogopite. In addition, minor quantities of' other minerals are frequently present. The obie'ce tives in'processing such materials are to recover a maximum of the available calcite and silica, and ,usually iron, and to eliminate all but a minor quantity of thecompounds of alumina, including the inagnesian silicates of alumina, whereby the recovered constituents maybe utilized as a cement raw material mixture, or'the major part thereof, for the production of modern cements, particularly those of low heat of hydration and resistant to sulphates. It may be said, therefore, that Portland cement'raw materials comprise'essentially a mixture of silica, alumina, iron, and calcium carbonate and to be commercially useful the calcium carbonate should represent about 77% of the total. In the beneficiation of cement raw;

- material it is desirable to obtain high weight rewater in we pulps as often required when the covery of the calcite of at least about 76% purity and at the same time reject a high proportion of the argillaceous compounds, usually silicate of alumina and quartz. past to economically produceconcentrates con- It has'been difficult in the The results in the above table indicate that only 0.5 pound of .the sodium soap or coconut oil fatty acid per ton of ore produced results which are better than those produced by using 2.00 pounds forming to the above standards using the ordi- 5 per-ton of ore of fish oil fatty acids or talloel. nary fatty acid type calcite collectors. The fol- The improved calcite promoter of the present lowing examples are specific illustrations of the i ventio may b used in conjunction with recent present invention in which satisfactory concen-wdevelopments i th treatment 1 cement raw trates were Produced undelf economical condimaterials. For example, when carbonaceous mations. It is to be understood, however, that the terials are to be treated the carbon may be first invention is not to be limited by the speciflccondispersed by t addition of carbon dispersers, on S f rth n e examplessuch as calcium lignin sulfonate prior to the froth Comparative froth flotation tests were fiotation using the promoter of the present invenducted with various reagent combinations on a om The promoters may likewise b d in sa e of ceme t w material f the Lehigh processes in which the. froth flotation tails are Valley Bluestone type the following mannersubsequently subjected to a froth flotation treat- The Ore charge Was ground to 93% minus 325 ment in the presence of a cationic promoter t mesh and 1.76% plus 200 mesh in a rod mill. The reduce the silica t t; a n p was Placed in Fagergren flotation In the above flotation tests it is seen that the machine. diluted to 22% Solids and conditioned low molecular weight sodium soap of coconut for one minute with calcium lignin oil is a much better calcite collector than the fon t per ton of ore. A concentrate was then h gh molecular weight soap of cottonseed oil. In floated by the addition (in 7 stages) of small similar 'tests we have determined t t the amounts of the promoter being tested. The total dium soaps of palm oil and palm kernel oil are time of flotation was 7 minutes. The results .ob-' 25 em ient calcite promoters, whereas the sodium tained are given in the following table. soaps of oils such as cottonseed, soya bean, olive,

Concentrate Telling Frotber Per cent Per cent Dist. Percent Per cent Dist. Promoter Lbs'lton lbs'lton weight 0800. 0800. Weight CaCO; 02:00;

04.53 74.15 97.68 5.42 30. 77 2.32 K-coconutoilsoa 0.70 0.128 83.14 81.04 94.67 16.86 22.51 5.33 Na-coconut oil soa 0.50 0.064 88. 54 78.42 97.28 ll. 40 16. 94 2. 72 Nacoconut oil soap 0. 54 0. 128 82.54 79.71 92. 74 17.46 29.52 7.26 NaOH and coconut oil fatt acid added separately 0.54 0.128

85.78 74.55 89.38 14.22 53.40 10. 02 Kcoconut oil soap 0.38 0.128 70.70 82.77 82.02 20.21 42.20 17.38 Na-coconut oil soap 0. as 0.128 34.29 79.10 39.45 65.71 05.70 60. 55 Nit-cottonseed oil soap 0.38 0.128

1 The irother used in the tests was a mixture of branched and straight chain aliphatic monohydric alcohols boiling between about 150 C. and about 165 C. obtainable by the catalytic hydrogenization of carbon oxides.

ter than the free fatty acids and also that the addition of the sodium soap as such to the flotation pulp is better than adding the fatty acid and caustic soda separately to the pulp.

Additional tests were run in which the carbon was floated off first by means of 0.128 lb. of frother per ton of ore. All of the promoter was then added and the resulting concentrate was skimr'ned off for two minutes. In the tests-using the free acid the NaOI-Iwas added separately.

. The results of these tests are given in the followpeanut, corn, and similar oils, which contain less than one fourth fatty acids having less than 18 carbon atoms, are not. We hav also beenable to show that the sodium soaps of individual fatty acids containing 16 or less carbon atoms are eihcient calcite promoters. This could not have been predicted since it is known that nonmetallic ore materials, such as for example phos phate rock, cannot be effectively promoted with the low molecular weight fatty acids.

In the processing of cement raw materials it is very important that the reagents employed be relatively inexpensive. We, therefore, prefer to use the sodium soaps produced by saponifying natural mixtures of fatty acid giycerides in which at least one third of the fatty acids present consist'of fatty acids containing not more than 16 palm kernel oil, and palm oil since the proportion of high molecular weight fatty acids, that 1 tabl I is to say, those having 18 or more carbon atoms,

Concentrate 't ge r c t Pr motor Lb n can 7 i o 5. n CaOO; Per cent Per cent f fggz' CaOO; weight 01100; 0,100

70.88 80.15 .09 85.92 83.10 0.50 I 73. 09 53. 02 81.22 58. 0c. 03 m 74.00 23. 57 77.]? 24. 73 73.42 200 "2,886,014 3 constitute not more than two thirds of the fatty argillaceous limestones, marls, and chalks which acids present. comprises subjecting an aqueous pulp of the ore We claim: to froth flotation in the presence of sodium soaps 1. The method of concentrating calcite by froth flotation which comprises subjecting an aqueous ore pulp containing calcite and siliceous gangue minerals to froth flotation in the presence of a reagent selected from the group consisting of the sodium soaps of fatty acids containing from 8 to 16 carbon atoms and the sodium soaps of mixtures of fatty acids in which at least one third of saidmixture consists of fatty acids, containing not more than 16 carbon atoms, said froth flotation being carried out in the absence of calcite activators.

2. The method of concentrating calcite by froth flotation which comprises subjecting an aqueous orepulp containing calcite and siliceous" gangue minerals to froth flotation in the presence of sodium soaps of fatty acids containing from 8 to 16 carbon atoms, said froth flotation being carried out in the absence of calcite activators. V V

3. The method of concentrating calcite by froth flotation which comprises subjecting an aqueous ore pulp containing calcite and siliceous gangue minerals to froth flotation in the presence of sodium soaps of mixtures of fatty acids in which at least one third of said mixtur consists of fatty acids containing not more than 16 carbon atoms, s'aid froth flotation being carried out in the absence of calcite activators.

4. The method of concentrating calcite from argillaceous limestones, marls and chalks' which comprises subjecting an aqueous pulp of the ore to froth-flotation in the. presence of a collector for the calcite, said collector being selected from the group consisting of the sodium soaps of fatty acids containing from 8 to 16carbon atoms and the sodium soaps of mixtures of fatty acids in which at least one third of said mixture consists of fatty acids containing not more than 16 carbon atoms, said froth flotation being carried out in the absence of calcite activators.

5-. The method of concentrating calcite from of fatty acids contaming'from 8 to 16 carbon atoms, said froth flotation being carried out in the absence of calcite activators. 4

6. Th method of concentrating calcite from argillaceous limestones, marls, and chalks which comprises subjecting an aqueous pulp of the ore to froth flotation in the presence of sodium soaps of mixtures of fatty acids in which at least one third of said mixture consists of fatty acids containing not more than 16 carbon atoms, said froth flotation being carried out in the absence of calcite activators.

7. The method of concentrating calcite from argillaceous limestones, marls, and chalks which comprises subjecting an aqueous pulp of the ore Y tofroth flotation in the presence of the sodium soaps of coconut oil fatty acids, said froth flotation being carried out in the absence of calcite activators.

8. The method of concentrating calcite from argillaceous limestones, marls, and chalk which comprises subjecting an aqueous pulp of the ore to froth flotation in the presenc of the sodium soaps of palm oil fatty acids, said froth flotation being carried out in the absence of calcite activators.

9. The method of concentrating calcite from argillaceous limestones, marIs,-and chalks which comprises subjecting an aqueous pulp of the ore to froth flotation in the presence of the sodium soaps of palm kernel oil fatty acids, said froth flotation being carried out in the absence of calcite activators.

10. A process according to claim 1 in which the reagent is stage fed into the aqueous ore pulp.

11. A process according to claim 1 in which carbonaceous material is removed from th ore Pulp prior to the froth flotation concentration of the calcite.

DAVID WALKER. .lAYNE. JR. SI'EPHEN EDWARD ERICKSON. HAROLD MILTON DAY. 

